Quantum Dot Labeling for Single-Cell Protein Quantification
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Solution Overview
Problem
Current methods for detecting and quantifying low-abundance cellular signaling proteins in single cells face challenges due to sensitivity limitations and the masking of individual differences within cell populations, making it difficult to assess therapeutic efficacy and understand cellular heterogeneity.
Innovation Solution
The use of discrete label complexes, such as quantum dots, for imaging and counting biomolecules at multiple depths, allowing for the calculation of activity levels in individual cells and providing relative activity levels across a sample, enabling sensitive quantification of signaling proteins and distinguishing intact cells from artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fluorescence methods are used for detecting signaling proteins, then detection can be performed in single cells, but sensitivity is insufficient to reliably detect low-abundance proteins above background noise
Solution Approach 1:
The patent uses discrete labels (quantum dots, fluorescent dyes) as intermediary markers that bind to signaling proteins. These labels amplify the detectable signal from low-abundance proteins while maintaining single-cell resolution, effectively mediating between the target proteins and detection systems to overcome background noise limitations
Solution Approach 2:
The patent changes the physical parameters of the detection system by using discrete labels with specific optical properties (quantum dots with size-dependent emission, fluorescent dyes with high quantum yield). This parameter change enables detection of low-abundance proteins by transforming the detection modality from conventional fluorescence to label-based signal amplification
2Measurement precision
If cell population-averaging techniques are used to boost detection sensitivity, then sensitivity increases, but individual differences among cells are masked
Solution Approach 1:
The patent segments the cell population into individual single-cell units for separate analysis. By using discrete labels that can be detected and counted in individual cells, the method maintains single-cell resolution while achieving sufficient sensitivity, thus preventing loss of cellular heterogeneity information that would occur with population averaging
Solution Approach 2:
The patent uses discrete labels as copies or proxies for the actual signaling proteins. Each label represents a specific protein molecule, and by counting labels in individual cells, the method reconstructs protein abundance information at single-cell resolution without requiring population averaging
3Productivity
If FACS is used for high-throughput single cell analysis, then throughput is high, but sensitivity for measuring signaling activation in intact cells is limited
Solution Approach 1:
The patent uses discrete labels as optical copies of signaling proteins that can be detected with high sensitivity. These labels enable measurement of signaling activation in intact cells with sensitivity superior to FACS, while maintaining the ability to analyze individual cells in high-throughput formats
Solution Approach 2:
The patent changes the detection parameter from flow cytometry-based fluorescence intensity measurement to discrete label counting in intact cells. This parameter change enables simultaneous achievement of high throughput and high sensitivity for signaling detection without the limitations of FACS
4Measurement precision
If discrete labels are used for single cell analysis, then sensitivity and cellular heterogeneity information are improved, but device complexity increases
Solution Approach 1:
The patent uses discrete labels as intermediary elements that simplify the detection process. By labeling target proteins with discrete markers, the complex task of detecting low-abundance proteins directly is transformed into a simpler task of counting discrete fluorescent or optical signals, thereby managing system complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances sensitivity beyond conventional fluorescence methods, enabling the detection of low-abundance proteins in single cells, distinguishing between intact cells and artifacts, and providing detailed insights into cellular heterogeneity and drug resistance, facilitating improved characterization of disease states and therapeutic responses.
Implementation Method 1
quantum dot phosphoassay (SC-QDP) platform that may be used to implement various methods described herein
Implementation Method 2
detecting and counting biomolecules using discrete labels such as quantum dots, fluorescent dyes and other punctate labels
Data Source
AI summary
Methods and systems for quantifying cellular activity using labeled probes, e.g., quantum dots, are disclosed. In one example approach, a method for quantifying cellular activity in a sample containing intact cells having labeled complexes comprises receiving images of the sample at a plurality of depths and detecting individual intact cells in the images of the sample at the plurality of depths. For each detected cell, discrete labels may be detected and localized in the cell at each depth, a total number of detected and localized labels may be calculated in the cell, and an activity level of the target molecule for the labeled probe in the cell determined.